extracting x bytes

keyops · 05-30-2004, 02:26 PM

Can anyone tell me if there is a way of greppin through a large file and - if grep finds the search term - it then extracts only x chars back and y chars forward?

The file I am searching is one large mass with no \n's, alike to a disk partition

ta

k

david_ross · 05-30-2004, 03:01 PM

I don't know of a way to do it with grep - I think it can only do line offsets. You could do something with perl:
perl -ne 's/(.....)(WORD)(...)/(print "$1$2$3\n")/meg;' SOMEFILE

Replace "SOMEFILE" with the name of your file and "WORD" with the word to search for. You can adjust the number of "."s to say how many characters before or after you want displayed. The example above will show 5 before and 3 after.

keyops · 05-30-2004, 03:07 PM

cheers for that - will give it a go

does anyone know how to do this at command line, rather than employing perl?

thanx again

Jc

david_ross · 05-30-2004, 03:08 PM

That command will work on the command line.

keyops · 05-30-2004, 04:30 PM

Agreed, but it is still employing perl

What I am wondering is whether or not this can be done with a combination of seeking through the file, using cut /sed/awk etc

if not, not a problem as your solution does work, but just interested in alternative shell examples

many thanks again

k